I have an application where I need to slide something linearly with some degree of accuracy but it has to be fast. I am using a linear slide like the one below
I want it to be able to move 15cm in under a second but the faster the better. For that I would need a motor with >1000RPM.
FIrst question, is there a stepper motor that fits my requirements? Would also need to have some torque to slide a load of 300 grams.
Second, I think I can do it with a DC motor and encoder because I need some torque as well and I can buy as big as I need cheaply. An issue I might have is that the object I want to move might be moved by external forces without me initiating the motion. I think optical encoders are not a good fit because I can't be sure which way it has moved, so I need an absolute encoder. Can you recommend a magnetic encoder for this application?
To move something, you must have some other support than a single point. What else is supporting your object and how is it able to support and let the object move?
Do you need two of your screw devices to move your object? Such a screw and nut as you picture resists any load movement unless the screw does the movement, so how can external force move your object?
Yes all this is fitted over a flat surface. The screw moves forward and backward when the rod turns and there is a metal piece that pushes or pulls an object. What I need is about 20N of horizontal force and to know exactly where the nut is.
Can you explain this a bit? Are you wanting to use a camera to see the nut or are you wanting to measure the distance of the nut from some point of it travel? Or what?
Fast means I want it to be able to run a distance of 150cm in one second (the threaded rod is 150mm long). Degree of accuracy means 2-3mm if possible. I have found linear encoders as an alternative, but I want to know if there is a way to do it with an absolute rotary encoder, and pick the best option. Ideally if you can suggest an off the shelf component that fits the requirements would be ideal, I've found the following
but I can't find one that is fast enough and the right length of 150mm. I have not tried a timing belt yet, I could try one combined with a sliding guide to see how well it works.
Interesting, I have found linear encoders but not draw wire encoders. Linear encoders seem a good option, I'm exploring rotary ones to keep the size of the whole thing as compact as I can. Do you happen to know which one is the more reliable of these two? Thank you
I don't really care about resolution in intermediate positions except for end points. I would like 2-3mm accuracy at the final position. I want to be able to program to go for example 9cm forward at max speed and I want to stop at 8.8-9.2 maximum (obviously 1mm would be ideal). I think if I know exactly where it is I can pull it back at a slower speed if it overshoots, main thing is to have feedback on where exactly it is
Yes ofc, no a camera won't do. I want to use a linear or rotary encoder to figure out where the nut is, it depends on how many revolutions the rod has made, (1 revolution moves it 8mm). Linear encoder is probably better but I'm trying to explore the option of a rotary one to keep it more compact
but with my own specs:
150mm long
150mm/s speed
1mm position accuracy
This will be mounted on a robotic arm to extend a tool. That tool may be pushed back as it is performing work. So I need to know if it has been moved unintentionally and fix the position.
